Charging damage in metal-oxide-metal capacitors

The magnetically enhanced reactive ion etching (MERIE) process is well known for causing charging damage to thin gate oxide. Damage to thin gate oxide by the Ar fillet process has been documented (Stamper et al., 1995). In this paper, charging damage to metal-oxide-metal (MOM) capacitors, often used in analog circuits, is reported. The dielectrics in these MOM capacitors are much thicker than gate oxides and the antenna ratios are typically near unity. One therefore does not expect these capacitors to suffer from charging damage easily. However, we found these MOM capacitors to be very sensitive to charging damage. We argue that the sensitivity of these capacitors is actually not surprising. Thicker oxides require higher voltage but less current to breakdown. Since antennae act as current amplifiers, thicker oxide does not require a large antenna ratio to become damaged as long as the plasma can supply the voltage. In addition, the dielectric in MOM capacitors is not of the same quality as gate oxides and therefore is more prone to damage.